A variety of externally heating fixing devices have been developed for directly heating the outer periphery of a roller or film facing a heater. One example is a fixing device described in Japanese Patent Application Publication No. 2011-133502, which heats a fixing roller at its heat nip between the fixing roller and a heater, and fixes a toner image onto a sheet at its press nip between the fixing roller and a pressing roller.
This fixing device includes a pivotable heater arm that supports a heater, a pivotable pressing roller arm that supports a pressing roller, and a spring that connects the arms. The arms are pulled toward each other by the spring to press the heater and the pressing roller against the fixing roller, thus forming the heat nip and the press nip. The device further includes a cam between the heater arm and the pressing roller arm. The cam rotates while pressing the heater arm and the pressing roller arm away from each other to release the nip pressure both at the heat nip and at the press nip.